I don't know of any ISPs that have classified as common carriers (although I know some common carriers who also run ISPs.
Part of the regulation that you have to accept as a common carrier is that you cannot perform any traffic control beyond what is required for stability, yes. But you also have to deal with a vast additional body of regulation having to do with connection between networks, international connections, etc. Getting the government to assign common carrier status to you is not a trivial business. Why would an ISP go through that?
scott
-- "C'est un Nagra. C'est suisse, et tres, tres precis."